In the field of radio communications, it is conventional to try to maintain the power at the output of a transmission line at a constant value, or, at the very least, to try to maintain constant impedances in order to guarantee the integrity of the signal all along the chain of a communications system.
However, owing to numerous factors, notably environmental, such as temperature, significant variations in power may be observed and compensation for those variations is desirable.
There exist means for compensating for these variations in power, such as for example through the use of an attenuator or attenuation cells placed between two successive blocks which regulate the amplitude of the transmitted signals as a function of a setpoint signal, whose value depends notably on the value of the output power and on the external conditions.
However, these attenuators have variable impedances, and the differences of impedance between these attenuators and the blocks which follow them lead to significant losses in the power of the signal and a degradation of the integrity of the signal. Moreover, the variation in impedance of the attenuators can interfere with the operation of the block that follows, for example an antenna.
There accordingly exists a need to effectively limit the variations in impedances within a transmission line for the purpose of guaranteeing therein a better control of power.